Improvement in bridges



. UNITED STATES ALBERT COTTRELL, OF NEWPORT, RHODE ISLAND.

IMPROVEMENT IN BRIDGES.

Specification forming part of Letters Patent N0. 43,099, dated June 14, 1864.

To all whom it may concern Be it known that I, ALBERT OOTTRELL, of Newport, in the county of Newport and State oflthode Island, have invented 'a new and useful Improvement in Forming or Constructing Wooden Viaducts or Bridges; and I do hereby declare the same to be fully" described in the following specification and represented in the accompanying drawings, of which- Figure l is a top view ot one-half of abridgeframe constructed in accordance with 'my invention. Fig. 2 is a side View thereof. Fig. 3 is a central and longitudinal section of it. Fig. 4 is a section taken longitudinally through one of the side beams or levers. Fig. 5 is a top view of one of the stretch or longitudinal timbers employed in making the side levers.

My invention is a peculiar combination and arrangement of bond timbers, counterbalanceweight supporters, screws, bolts, and stretchers of two side beams or levers, the whole constituting the half of a bridge-traine of the nature termed a counterbalanced bridge.7 In constructing a bridge of this kind it is commenced on eachabutment and built out` and projected therefrom over the stream or river without the employment of any piers, or centering the portion projected over the river and beyond the abutment, being balanced or sustained by means of stones orheavy weights laid on a timber or part caused to project in rear of the abutment. As the two halves of the bridge approach each other they will curve more or less, and when completed may be connected `over the middle ot' the stream and will present an arched form. By means of my invention viaduets or bridges of this nature and of very long spans can be constructed with great ease and safety, and with little cost, and when completed they possess much rigidity and strength.

I am aware that in its details ot construction, when separately considered, my im proved bridge does not possess novelty, but when considered collectively and in their arrangement and application its particular parts constitute a novel bridgeframing.

In my arrangement of the stretchers of my said bridge-frame I first determine the disi tance the'inner iowermost stretcher of each range is to lap by that on which it rests. If

Iwe suppose, for instance, this overlap to be `five feet, I usually make the length of each stretcher equal to three and one-half (or about Ouehalf) times such distance. In Fig. 5, D represents such distance, itbeing that at which each hole is to be bored through the stretcher is from the hole next to it. Four of such holes are next bored down through the stretcher, as shown at x x as x, each hole which is nearest to the end of the stretcher being situated at one-fourth, orabout-one-fourth of D from such end. Every one ofthe longitudinal timbers in each side lever should be made and bored alike. j.

In building the bridge-frame I usually com. mence by laying two supporting sills, a a., on the abutment b, (see Figs. 2, 3, and 4,) each of such sills being properly inclined to the horizon, and made to project beyond the abutment, as shown in such drawings. I next lay longitudinally upon each of such sills a a a stretcher, c, and lap it by the front end of the sill the distance D. Next I bolt each of such timbers or stretchers c downto its sill and cause it to lap over the rearend of the sill, as shown in the drawings. Next I lay on each timber c another stretcher, cl, and lap it a distance, D, beyond the front end of the stretcher c. Against the rear ends of the stretchers d d, I lay transversely a bond timber, e. Afterward I continue t) arrange the stretchersand bond timbers in manner as shown in the drawings, being careful to secure the inner end of each stretcher to three other stretchers immediately over it by means of an iron screw, f, or ascrew-bolt. I also not only bolt each ot' the stretchers to one or more of those immediately beneath it,

which I term counterbalance-weight supporters,77 each ot1 the latter being secured to four of the stretchers by two screw-bolts, one of which is shown ati in Fig. 4. It is on the series of timbers h h that the counterbalance stones or weights are to be laid as the build ing ofthe bridge may progress, the structure under such circumstances being erected both in front and rear of the abutment, as shown in the drawings.

The two halves of the bridge, being commeneed on their respective abutments and afterward constructed so as to approach one another, may, when completed, be so lapped on and suitably connected to one another as to form a single structure, on which the Hoortimbers and flooring for the bridge may be laid. More stretchers, if necessary, may afterward be laid on each side beam, and be connected together so as to constitute parapets for the bridge, and also add to the strength of the whole.

By building backward, orlayin g each course 0f Astretchers and bond timbersbackward toward the abutment, we are enabled to adjust the timbers together to better advantage than would be the case were we to pursue an opposite course. The heads of the screws and the bolts of the front stretcher of each course of stretchers are covered by the stretehers which rest directly on them, each of suoli screws going through three stretehers, and not being put in place until the three stretch ers are laid.

I claimv The above-described combination and arrangement ofthe bond timbers, the balanceweight supporters, the screws, bolts, and stretchers ofthe two side beams or levers, the whole constituting the half of a bridge-frame of the character speoied.

ALBERT COTTRE LL.

Witnesses:

R. H. EDDY, F. P. HALE, Jr. 

